1 76 On Steam and Brines 



of Blagden's law, whether applied to freezing or boiling. The 

 deviations from Blagden's law in freezing and in boiling 

 solutions may be attributable to some deviation from the 

 law that the capacity for heat of a saline solution is the 

 capacity for heat of the water which it contains. It is easy 

 to obtain from the values of W (t T) in Table IV what must 

 be the specific heat of the saturated water which would make 

 W(t- 7*) constant 1 . 



Table V gives for dilute solutions what Table IV gives 

 for strong solutions. As the values of (t- T) are not exactly 

 the same for each salt, the relations of (t T) and W(t T) 

 were expressed by curves and the values of W (t T) taken 

 from them for the same values of (t - T) for every salt. These 

 values are given in Table VI. In all the experiments of 

 Table V, exactly one-twentieth of a gramme-molecule of 

 salts was taken, and the weight was exact to the nearest 

 milligramme, and the experiments were made in every way 

 alike. Table V contains no mixtures ; on the other hand, 

 some simple salts are included which are not found in Table 

 IV. They are LiCl, RbCl, CsCl, KI, KBr, KNO 3 , and AgNO 3 . 

 Both the RbCl and the CsCl were " spectroscopically pure," 

 and the caesium salt was quite pure. The rubidium salt, how- 

 ever, contained sulphate, and it is struck out in Table VI. The 

 detailed discussion of these results, as well as of those in Table 

 IV, must stand over to the second part of this paper, but one 

 or two facts may be pointed out. In the case of salts for 

 which the values of W(t 7^) diminish as dilution increases, 

 a minimum is reached when (/ T) is something between o7 

 and i'O C., after which it increases in all so that for values of 

 (t- T) between o'5 and i'2 C. the values of W(t- T} for all 

 these salts are practically constant, and they follow Blagden's 

 law. In the case of nitrates W(t- T) generally increases with 

 dilution, and a minimum, if it exists, would have to be sought 

 in solutions saturated under high pressure. Strontium nitrate 

 is an exception ; it has a minimum at I 0> o C. 



In Table VII will be found the values of/, the vapour 

 tension of pure water at the temperature (/) of the boiling 



1 See below in Note, p. 184. 



